An inductor is a representative passive element configuring an electronic circuit together with a resistor and a capacitor. As miniaturization and thinness of electronic devices have accelerated along with the development of information technology (IT), market demand for small, thin elements has increased, and the capability of implementing high inductance and low direct current resistance characteristics have also been required in inductors.
Among these inductors is a thin film inductor. The thin film inductor is manufactured by forming a coil on a support, stacking a plurality of magnetic sheets on both surfaces of the support, and compressing the stacked magnetic sheets.
The magnetic sheet is formed of a composite of a metal powder or ferrite powder and a resin. In the case of the present application, since the metal powder has high inductance and low direct current resistance as compared to the ferrite powder, the range of uses of metal powders has further enlarged.
A stacked body compressed as described above is manufactured in a form of a bar by optimizing a filling rate using two or more kinds of powders having different particle sizes, filling empty pores with an epoxy resin, and then allowing a hardening process to occur.
When the bar is manufactured as described above, a shape of the bar may be deformed. Under the assumption that the manufactured magnetic sheet is stable in terms of quality, deformation of the bar primarily occurs when a residual solvent contained in the magnetic sheet is volatilized, to thereby be released during drying of the bar, and dry shrinkage of the resin in the magnetic sheet occurs. In addition, the deformation may occur due to hardening shrinkage by a hardening reaction among the resin, a hardener, or a hardening accelerator of the magnetic sheet during the hardening.
Particularly, deformation of the bar due to the hardening shrinkage has been a problem, and when the bar is excessively deformed, the bar is in a state in which a coil disposed in the bar is moved excessively as compared to a desired amount.
Therefore, even though the bar is diced using a compensation value in a dicing process, which is a process subsequent to the hardening process, the possibility that a terminal exposure defect will frequently occur, due to misdicing of a chip, may be large. Therefore, research has been conducted into a technology capable of controlling the hardening shrinkage described above to decrease the deformability of the bar.